Hydrocracking process with integral intermediate hydrogen separation and purification

Abstract

An intermediate hydrogen separation and absorption-based purification system is integrated with a hydrocracking process for the production of relatively lower molecular weight products from a relatively heavy feedstock including sulfur-containing and nitrogen-containing hydrocarbon compounds. The integrated process allows the processing of heavy hydrocarbon feedstock having high nitrogen and high sulfur contents in a single-stage configuration and the using of noble metal catalyst in the hydrocracking reaction zone. The integrated process increases the overall catalytic activity and hydrogenation capability to produce superior distillate products.

What is claimed is: 
     
       1. An integrated hydrotreating and single-stage hydrocracking process comprising:
 a. hydrotreating a feedstock with a hydrotreating catalyst in the presence of hydrogen to produce a hydrotreated effluent containing a reduced amount of sulfur-containing and/or nitrogen-containing hydrocarbon compounds as compared to the feedstock; 
 b. separating the hydrotreated effluent in a high-pressure separation zone to produce a vapor stream and a hydrocarbon liquid stream; 
 c. purifying at least a portion of the vapor stream in an absorption zone in the presence of at least a portion of relatively heavy components of the vapor stream from step (b) to produce a high purity hydrogen gas stream and a fuel gas stream; 
 d. hydrocracking at least a portion of the hydrocarbon liquid stream from step (b) with a hydrocracking catalyst in the presence of hydrogen gas in a single-stage reactor configuration to produce a hydrocracked effluent, wherein the hydrogen gas includes at least a portion of the high purity hydrogen gas stream from step (c); and 
 e. separating and fractionating the hydrocracked effluent. 
 
     
     
       2. The process as in  claim 1 , where step (b) comprises separating the hydrotreated effluent in a hot high-pressure separation zone to produce a gas stream and a hydrotreated liquid stream, and separating the gas stream in a cold high-pressure separation zone to produce a vapor stream, a hydrocarbon liquid stream and a sour water stream, wherein the relatively heavier components of the vapor stream used in step (c) are derived from the further condensation of the heavier fractions in the vapor stream generated from the cold separator and additional make up provided by the portion of the hydrocarbon liquid stream from the cold high-pressure separation zone. 
     
     
       3. The process as in  claim 2 , wherein step (d) comprises hydrocracking the hydrotreated liquid stream from the hot high-pressure separation zone and at least a portion of the hydrocarbon liquid stream from the cold high-pressure separation zone. 
     
     
       4. The process as in  claim 3 , wherein step (e) comprises
 separating the hydrocracked effluent into a gas stream and a hydrocracked liquid stream; 
 flashing the gas stream and the hydrocracked liquid stream to produce a flashing overhead stream, a flashing liquid stream and a flashing bottom stream; 
 fractionating the flashing liquid stream to produce a fractionating overhead stream, a first side-stream, a second side-stream and a fractionating bottom stream; 
 recycling at least a portion of the fractionating bottom stream to step (d); and 
 recovering the fractionating overhead stream, the first side-stream, the second side-stream, and at least a portion of the fractionating bottom stream as products. 
 
     
     
       5. The process as in  claim 2 , wherein step (d) comprises hydrocracking at least a portion of the hydrotreated liquid stream from the hot high-pressure separation zone and at least a portion of the hydrocarbon liquid stream from the cold high-pressure separation zone. 
     
     
       6. The process as in  claim 5 , wherein step (e) comprises
 separating the hydrocracked effluent and at least a portion of the hydrotreated liquid stream from step (b) into a gas stream and a hydrocracked liquid stream; 
 flashing the gas stream and the hydrocracked liquid stream to produce a flashing overhead stream, a flashing liquid stream and a flashing bottom stream; 
 fractionating the flashing liquid stream to produce a fractionating overhead stream, a first side-stream, a second side-stream and a fractionating bottom stream; and 
 recovering the fractionating overhead stream, the first side-stream, the second side-stream, and the fractionating bottom stream as products. 
 
     
     
       7. The process as in  claim 4 , further comprising compressing the flashing overhead stream in a recycle hydrogen compressor to produce compressed recycle hydrogen, and recycling the compressed recycle hydrogen to step (a). 
     
     
       8. The process as in  claim 4 , further comprising compressing the flashing overhead stream in a recycle hydrogen compressor to produce compressed recycle hydrogen, and recycling the compressed recycle hydrogen to step (d) so that hydrocracking in step (d) occurs in the presence of both the compressed recycle hydrogen and the high purity hydrogen gas stream from step (c). 
     
     
       9. The process as in  claim 8 , further comprising providing make-up hydrogen for hydrocracking in step (d). 
     
     
       10. The process as in  claim 6 , further comprising compressing the flashing overhead stream in a recycle hydrogen compressor to produce compressed recycle hydrogen, and recycling the compressed recycle hydrogen to step (a). 
     
     
       11. The process as in  claim 6 , further comprising compressing the flashing overhead stream in a recycle hydrogen compressor to produce compressed recycle hydrogen, and recycling the compressed recycle hydrogen to step (d) so that hydrocracking in step (d) occurs in the presence of both the compressed recycle hydrogen and the high purity hydrogen gas stream from step (c). 
     
     
       12. The process as in  claim 11 , further comprising providing make-up hydrogen for hydrocracking in step (d). 
     
     
       13. The process as in  claim 1 , wherein a portion of the hydrocarbon liquid stream from step (b) is passed to step (e) without hydrocracking.